Perioperative Neurocognitive Disorders

Umbrella term encompassing:

• Post-Operative Delirium
  Delirium occurring within 1 week post-procedure, and where other causes of delirium have been excluded.
• Delayed Neurocognitive Recovery
  Cognitive dysfunction occurring after surgery and up until 30 days post-operatively.
• Post-Operative Cognitive Dysfunction
  Cognitive dysfunction persisting after 30 days post-operatively. Graded based on extent of cognitive deficit into:
  • Mild
  • Major

Risk Factors

Predisposing factors:

• ↑ age
• Low premorbid IQ
• Lower education level
• Perioperative covert stroke
• Hearing or visual impairment
• Comorbidities
  • CVD
  • IHD
  • PVD
  • DM
  • Anaemia
  • PD
  • Depression and anxiety disorders
• Poor functional state
• Polypharmacy
• Use of psychotropic medications
  • Benzodiazepines
  • Anticholinergics
  • Antihistamines
  • Antipsychotics

Precipitating factorsL * Procedural * Hip fracture surgery * Aortic surgery * Prolonged surgery * Physiological * Hypoxia * Hypercarbia * AKI * Prolonged fasting * Infection * Hypothermia * Electrolyte abnormalities * Other * Alcohol * Sleep deprivation * IDC * Poor nutrition * Urinary retention

Management

Preoperative: * Assess risk * Consider geriatric referral
Associated with reduced incidence of POCD.

Intraoperative: * Consider propofol TIVA * Consider light sedation over deep sedation * No evidence for benefit of neuraxial over GA * Consider BIS target 40-60 for GA * Avoid intraoperative hypotension

Postoperative: * Non-pharmacological * Orientation * Early mobilisation * Non-pharmacological approaches * Prevention of sleep deprivation * Hearing aids and glasses * Pharmacological * Antipsychotics
Minimise use as they may worsen delirium.

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References

1. Mrkobrada M, Chan MTV, Cowan D, et al. Perioperative covert stroke in patients undergoing non-cardiac surgery (NeuroVISION): a prospective cohort study. The Lancet. 2019;394(10203):1022-1029. doi:10.1016/S0140-6736(19)31795-7
2. Evered L. Recommendations for the nomenclature of cognitive change associated with anaesthesia and surgery-2018. :8.
3. O’Hare K, Brinkmann S, Currigan D. Postoperative Delirium. Australian Anaesthesia. 2019.